Exhaust muffler

ABSTRACT

This invention relates to an improved sound dampener or muffler primarily useful in reducing the noise level resulting from exhaust gases. The invention has particular applicability to the reduction of noise produced by pneumatic tools such as air hammers, air drills and air wrenches.

Elnited States Patent 1 Hilbush, Jr.

1 EXHAUST MUFFLER [75] lnventor: Edward O. Hilbush, .113, West Chester,Pa.

[73] Assignee: West Chester Chemical Company,

lnc.,Pa.

[22] Filed: Oct. 11, 1973 [21] Appl. No.: 405,401

[52] US. Cl ..181/36 A; 181/33 G; 161/161 [51] Int. Cl, 111 0111 3/06[58] Field of Search 181/33 G, 36 R, 36 C;

[56] References Cited UNlTED STATES PATENTS 2,278,733 4/1972 Deik 181/33G 2,726,977 12/1955 See et a1. 161/112 2,728,702 12/1955 Simon et a1181/33 G 2,828,235 3/1958 Holland et al. 181/33 G July 29, 19753,202,239 8/1965 Clarke 181/36 R 3,211,253 10/1965 Gonzalez 181/33 G3,341,887 9/1967 Tolmie 161/161 3,466,222 /1969 Curtis 161/161 3,698,58710/1972 Baker et a1. 161/161 3,713,474 1/1973 Orlando 181/33 G 3,770,56011/1973 Elder et a1. 181/33 G Primary ExaminerStephen J. TomskyAssistant ExaminerVit N. Miska Attorney, Agent, or Firm-Hyde W. Ballard[57] ABSTRACT This invention relates to an improved sound dampener ormuffler primarily useful in reducing the noise level resulting fromexhaust gases. The invention has particular applicability to thereduction of noise produced by pneumatic tools such as air hammers, airdrills and air wrenches.

5 Claims, 7 Drawing Figures PATENTED JUL 2 91975 SHEET EXHAUST MUFFLERPRIOR ART OBJECT OF THE lNVENTION The present invention provides animproved article of manufacture for muffling the noise caused byvarious' types of equipment and'especially pneumatic jack hammers suchas commonly employed in breaking up paving, mortar and the like. It hasbeen found that continued exposure to the noise generated by suchequipment has a harmful effect upon the operator after periods of timeand it has, therefore, been necessary to re ,quire only limited use notexceeding a time felt to be -reasonably safe for the operator. With theimproved muffler of this invention, the 'noise level is reduced to thepoint that far greater production can be obtained with less fatigue andharmfuleffects.

By providing a laminated covering for the exhaust ports of a pneumatictool comprised of several layers of sound-deadening material selected toact in combination for maximum noise suppression, I have achieved afarsuperior muffler than those produced heretofore.

" The primary object, therefore, of the invention is to provide as anarticle of manufacture a sound-deadening material which is rugged, hashigh sound-deadening properties, is easy to install and remove from apneumatic tool, and which is relatively lightweight and inexpensive.

DESCRIPTION or THE DRAWINGS Referring now more particularly to thedrawings,-

" FIG. ll"illustrates,the conventional pneumatic drill or jack hammer onwhich the muffler of the present invention is] desirably used, I I

FIG. 2 illustrates the pneumatic tool of FIG. 1 with the 'mufflerinstalled thereon,

FIG. 3 is an enlarged sectional as seen at 3--3 of FIG. 2 showing themuffler only, the pneumatic tool being indicated in broken lines,

F IG. 4 shows the muffler of FIG. 2 in its unrolled condition,

FIG. 5 is an enlarged sectional detail as seen at 55 of FIG. 4,

H6. 6 is an exploded view showing the various laminations which comprisethe muffler of FIG. 2, and

FIG. 7 is an enlarged sectional detail as seen at 7-7 of FIG. 6.

It will be understood that the muffler material as described hereinafteris illustrated as applied to the conventional pneumatic jack hammersince this is one of the most objectionable pneumatic tools from thestandpoint of noise and operator fatigue. However, my improved laminatedmuffler can be used to equally good advantage on other pneumatic tools,internal combustion engines and as a sound-deadening material forsimilar devices.

The conventional pneumatic jack hammer 10 comprises a cylinder 11, ahandle 12 attached to the upper end of the cylinder, suitable airhoseand inlet connections 13, exhaust ports 14, 14 and a reciprocatingpiston assembly 15 utilizing one or more compression springs 16. A drillor hammer or other suitable tool 17 is secured at the bottom of thepiston 15 by means of a clamp and bolt 18. The particular pneumatic tooldescribed herein is merely representative of various types and sizes ofpneumatic tools to which the invention can be applied.

A muffler assembly 20 is wrapped around the cylinder 11 of the pneumatictool so that it encloses the exhaust ports l4, 14. The muffler 20 isprovided with a plurality of apertures 21, 21 which permit the escape ofexhaust gas through the non-porous portion of the muffler 20. Theexhaust ports 21 are preferably spaced axially from exhaust ports 14 andmay also be turned radially 180 therefrom in order to provide asubstantial travel through the muffler, thus enhancing thesound-deadening property thereof. Muffler 20 is conveniently secured tocylinder 11 by means of one or more straps 25, 25 which are held indouble D rings 26, 26.

Referring now more particularly to the F105. 6 and 7, the muffler 20comprises an outer impregnated cloth or fabric 27 which is preferably aneoprene coated woven nylon material from 0.005 inch to 0.015 inch Thesetools receive extremely rough treatment and are constantly thrown ordropped on sharp material such as concrete or stones. The fabric layer27 can, of course, be of other natural or synthetic material, but

nylon is preferred due to its high strength and elasticity whereby itcan withstand shock and distortion. Likewise, the neoprene coating isnot essential, but other elastomeric materials could be used, forexample, natural rubber, butyl rubber or acrylonitrile. It will beunderstood in the event that when the improved muffler is to be used insituations where the possibility of damage or hard usage may not bepresent, the protective coating or layer 27 can be modified oreliminated.

The next lamination 28 is sheet lead, preferably 0.0075 to 0.015 inchthick. Here again, the preferred thickness of lead sheet 28 may bevaried depending upon the extent of the muffling required in view of thenoise level and also on the type of surface on which the tool is to beused. In such situations, other nonresonant sheet material could beemployed such as tin, bismuth, zinc, copper or aluminum, the primaryrequirements being that the sheet lamination 27 be annealed sufficientlyso that it can be shaped around the object or tool and also benon-resonant. The fabric layer or lamination 27 may be secured to themetallic layer 28 by means of a suitable adhesive depending upon thematerials employed.

The third layer 29 comprises a porous sheet 30 which is securely encasedin a fabric material 31 by means of stitching shown at 32 or staples,33, 33. The casing 31 may also be a neoprene coated nylon fabric havinga thickness between 0.005 inch and 0.015 inch. The porous material 30 isdesirably a layer of flexible opencell polyurethane sponge. This isimportant from the standpoint of diffusing the exhaust gas evenlythroughout the muffler and/or at least around the periphery, bothaxially and radially of the pneumatic tool exhaust ports. Flexibility ofthe muffler as a whole is important to enable it to be wrapped aroundthe various irregularities and protrusions of the particular tool towhich it is applied. It may be desirable to use a thicker porousmaterial 30 on larger tools but for heavy pneumatic tools, thickness forthe porous material ranges from 1 inch to 2 inches.

It will be understood that the apertures 21 in the muffler assembly 20must be provided through the metallic sheet and also through the variouscoated fabrics provided they are non-porous. However, the apertures donot extend through the porous material 30. FIG. shows the apertures 21extending through the layers 27, 28 and the outside portion of the case31 for the porous material 30.

It will thus be apparent that I have provided an improved laminatedmaterial for reducing or deadening the noise emitted by various devices,particularly those discharging fluid at high velocity such as pneumatictools, internal combustion engines and the like.

Having thus described my invention, 1 claim:

1. A sound-deadening laminated article of manufacture for use in themuffling of exhaust gas noises comprising an inner first sheet offabric, an intermediate second sheet of open cell, elastomeric materialsecured to the surface of said inner first sheet, a third sheet offlexible lead of a thickness in the range 0.0075 inch to 0.015 inchsecured to the surface of the sheet of elastomeric material, and anouter sheet of fabric secured to the surface of said flexible leadsheet.

2. The article of claim 1 in which the outer sheet of fabric is wovenNylon and is impregnated with neoprene and which has a thickness in therange of 0.005 inch to 0.015 inch.

3. A muffler for a pneumatic tool having at least one exhaust portcomprising an inner sheet of open cell elastomeric material. a fabriccasing for said elastomeric sheet. a second sheet of flexible sounddeadening metal. an outer third sheet of protective impregnated fabric,means for laminating said sheets together. and means including at leastone strap for securing said laminated sheets to the pneumatic toolcovering the exhaust port.

4. A muffler in accordance with claim 3 in which the metallic sheet isprovided with at least one aperture to permit passage of exhaust fluidtherethrough.

5. A muffler in accordance with claim 4 in which the aperture is offsetaxially from the exhaust port.

1. A sound-deadening laminated article of manufacture for use in themuffling of exhaust gas noises comprising an inner first sheet offabric, an intermediate second sheet of open cell, elastomeric materialsecured to the surface of said inner first sheet, a third sheet offlexible lead of a thickness in the range 0.0075 inch to 0.015 inchsecured to the surface of the sheet of elastomeric material, and anouter sheet of fabric secured to the surface of said flexible leadsheet.
 2. The article of claim 1 in which the outer sheet of fabric iswoven Nylon and is impregnated with neoprene and which has a thicknessin the range of 0.005 inch to 0.015 inch.
 3. A muffler for a pneumatictool having at least one exhaust port comprising an inner sheet of opencell elastomeric material, a fabric casing for said elastomeric sheet, asecond sheet of flexible sound deadening metal, an outer third sheet ofprotective impregnated fabric, means for laminating said sheetstogether, and means including at least one strap for securing saidlaminated sheets to the pneumatic tool covering the exhaust port.
 4. Amuffler in accordance with claim 3 in which the metallic sheet isprovided with at least one aperture to permit passage of exhaust fluidtherethrough.
 5. A muffler in accordance with claim 4 in which theaperture is offset axially from the exhaust port.